I know this post is way too old, but recently our datacenter changed their entire IP range and this is what we did.

Note: For this example, I assume that you are using a regular Linux Distro (RH/CentOS/FC) and have the /usr/bin/replace command which comes with MySQL-server.xx.rpm. I also assume that your datacenter has configured both old aswell as the new networks on their router.

Once this script runs successfully, we will change the base IP address of the system. Assuming that your main interface is eth0, edit the file /etc/sysconfig/network-scripts/ifcfg-eth0 and carefully change the IP, Broadcast, Netmask, etc. to that of the new IP range.

Everytime I have used the change mutli account ips script I have to limit it to no more than 4 sites at a time and if a large site do only 1 at a time or the script will hang and then have to do the kill -9 pid on all hung processes and start over